Are Lowthers a "full range listening" speaker?

I think the short answer to your question is "no". You cannot expect a Lowther system to reproduce the lower octaves unless you have extremely large cabinets. That said, I find that coupled to a good subwoofer to handle the lower frequency extremes, one of these systems will provide one of the most musical listening experiences possible. I was on a continuous upgrade path until I discovered the glory of a Lowther/SET system with a high quality sub. I know it is a matter of taste since all sytems are compromised to some extent, but it works for me.

Herman is so right! So as Lowther based system, even without the SUB. Much closer to the 'real thing' than any conventional set-up. Why? Dunno, even with many obvious faults Horn (folded)/ SET is as good as you can get. Check the official Lowther web-site, and you can see numerous Lowter based plans. I listened Beauhorn Virtuoso, and i am convinced that 80hz is enough. For me!

Herman and Eldragon: Guess I should clarify~question refers to a full range of music, not frequency response. Thanks for comments. What kind of sub, and did that help mainly rythmic drive? Getting ahead of myself, but.....

I would say that if you mean "fullrange" to include the lowest octave(20Hz-40Hz), the answer would be no. But for my tastes, I would say that the Lowther/Voight Pipe system I have is quite satisfactory for "broad listening". I have not had any extended listening exposure to the BD AER or Reps-1 drivers or systems, so I cannot really give you insight into those systems, although I think they also have good merit, but are still limited to similar frequency range as Lowther. Since the new series of Lowther drivers have improvements in key areas over previous models, any advantages that may have been attributable to AER or Reps is now negligable in my opinion. Any of these brands will provide very nice crossoverless sound in a good cabinet design. They will play quite loud with low wattage, and give extraordinarily good sound quality and detail. At this time, I am very satisfied with the sound I am getting from my Voigt Pipes, and am not looking to change drivers in the foreseeable future.

I have not considered the Oris horns at all because they do not fit my requirement for single-driver system. Also, I am not a fan of front loaded horns, although I have heard good reports of the Oris not being as "honky" as most. The real disqualifier for them to me, is the multi driver arrangement. Many people feel that the extension into the bottom octave is worth having the crossover and extra drivers in the system. I don't feel that way. I prefer the coherence and point source of a single driver crossoverless system, and am willing to accept the 40Hz lower limit. That is just my personal preference. Nothing is perfect, and I would prefer seamless coherence in 90% of the spectrum, than to sacrifice that to get the lowest 10% of the least used area of the spectrum. Others, no doubt, feel differently. Obviously, I would like to have it all, but that is not possible at this time from a fullrange cone driver. Soundlabs provides single-driver planar that reaches deeply into the bottom octave, but requires a high power amplifier, and this requires a trade-off in that area. I feel that for my needs, which include a very wide variety of music, that the Lowthers with my SET ZOTL 45 amp provides the maximum transparency and coherence for my music, with the least objectionable trade-offs for me. This is considering everything together as a package. To go with any other method, would require either a higher power push-pull amp, or crossovers and multi-drivers, or both. Or possibly even a bi-amp system. All of these alternatives create problems that I consider to be more deleterious to the musical presentation than the lack of 20 cycles of response in the bottom octave. I am getting a very solid 40Hz lower cutoff, and many speakers that claim full range are actually rolling off around there anyway. The vast majority really only will get to the lower 30s, even if they claim lower. When you try to integrate a subwoofer, there are loads of problems that are the subject of endless threads on this forum. So "you pays your money, and you takes your chances" as the carnival barkers say. I'll stick to the path of least interruption and corruption of the signal. If that means I have to give up a few cycles in the bottom end, so be it.

Regarding the Hedlunds, I have the plans on hand to make them, but they are a true rear horn, where the Voigt Pipes are not. Voigt Pipes are a combination of rear horn, transmission line, and bass reflex. This big knock on the Voigt Pipe is the comb-filtering effects created by the interaction of the port and the direct radiating driver. In practice, I have not found this to be a problem in my system. My Pipes are modified for improved wave-launch and acoustical baffle-step compensation. Perhaps this has mitigated the problem, but I don't have any noticeable comb-filtering effects with my system. All systems are a compromise, and I tried to provide the cleanest, most direct signal path that I could, and powered it with a SET OTL amp that is not even available, and had to be custom built by the only person that can build one, David Berning. The match seems to work quite well. If a person wants to modulate the walls with high SPL subsonic bass, then this is not the system to choose. If a person wants to have the least interference and corruption of the musical signal during playback, then this is a very enjoyable route to take. To each his own.

Thanks TWL for such a thorough answer! This looks to be a great forum and site in general. The descriptions of the "immediacy" of the Lowther sound really pique my curiosity. Coherency as well. Though I must admit I like to "modulate the walls" occasionally, I really only enjoy volume when it is very clean, and not continually. Musicality matters more!
Where are plans for the Voight Pipes with modifications available from, or were they your own experiments? Do you recommend a driver that is compatible with the Pipes?